1. Field of the Invention
The present invention relates to a semiconductor processing apparatus processing single or plural semiconductor substrates at a time; particularly to a mechanism supporting a semiconductor substrate inside a reaction chamber.
2. Description of the Related Art
In a semiconductor device processing process of today, a processing apparatus, which processes a semiconductor wafer by the piece, predominates. Generally in a single-wafer-processing apparatus, a susceptor is disposed inside a reaction chamber which can be kept airtight, and processing is performed to a semiconductor wafer being placed on the susceptor while the wafer is heated at a given temperature.
A typical susceptor in a single-wafer-processing apparatus is comprised of a disk made of a metal having high thermal conductivity or ceramics and has a heating element such as an electric heater built in. This type of susceptor has at least three through-holes, and substrate lift pins are inserted in the respective through-holes. When a semiconductor wafer is transferred into a reaction chamber by an external transfer system, the substrate lift pins move upward and protrude from the through-holes to receive the semiconductor wafer; subsequently, they move downward to place the semiconductor wafer on the susceptor. Additionally, when a processed semiconductor wafer is transferred from inside the reaction chamber to the outside, the substrate lift pins move upward again and protrude from the through-holes to support the semiconductor wafer and the semiconductor wafer is transferred to outside the reaction chamber by the transfer system.
In order to receive and deliver a semiconductor wafer on a susceptor, several different methods of sending a substrate lift pin up to protrude it from an upper surface of a susceptor are used.
The simplest method is to attach a lower end of the substrate life pin on a bottom portion of a reaction chamber to move the susceptor up and down.
It is designed that a substrate lift pin protrudes from an upper surface of a susceptor as the susceptor comes down.
In a different method, a lower end of a substrate lift pin is not attached and is moved up and down by a movable plate engaged with a lower end of the substrate lift pin; further, a susceptor can be moved up and down simultaneously with the lift pin. In this method, the lift pin has a structure of being suspended from the susceptor.
With these methods, methods with several improvements/modifications made have also been presented, in which functions are upgraded.
These substrate-supporting mechanisms are described in U.S. Pat. Nos. 5,421,893, 6,190,113, 6,995,741, 6,435,798, Japanese Patent Laid-open No. 2005-150725, etc.